#pragma once
#include<iostream>
#include<assert.h>
#include <cassert>
#include<thread>
#include<algorithm>
#include <mutex>
#include<vector>
#include<unordered_map>
#include<thread>
using std::cout;
using std::endl;
#ifdef _WIN32
	#include<windows.h>
#else 
	//linux
#endif
static const size_t MAX_BYTES = 256 * 1024;
static const size_t NFREE_LISTS = 208;
static const size_t NPAGES = 129;
static const size_t PAGE_SHIFT = 13;
#ifdef _WIN64
typedef unsigned long long PAGE_ID;
#elif _WIN32
	typedef size_t PAGE_ID;
#else //linux

#endif 
//直接去堆上按页申请空间
#ifdef _WIN32
#include<windows.h>
#else
//
#endif

//直接去堆上按页申请空间
inline static void* SystemAlloc(size_t kpage)
{
	void* ptr;
#ifdef _WIN32
	ptr = VirtualAlloc(0, kpage << 13, MEM_COMMIT | MEM_RESERVE,
		PAGE_READWRITE);
#else
	// linux下brk mmap等
#endif
	if (ptr == nullptr)
		throw std::bad_alloc();
	return ptr;
}

inline static void SystemFree(void* ptr)
{
#ifdef _WIN32
		VirtualFree(ptr, 0, MEM_RELEASE);
#else
// sbrk unmmap等
#endif
}


static void*& NextObj(void* obj)
{
	return *(void**)obj;
}

class FreeList
{
public:
	//管理切分好的小对象的自由链表
	void push(void* obj)
	{
		assert(obj);

		//头插
		//*(void**)obj = _freelist;
		NextObj(obj) = _freeList;
		_freeList = obj;
		++_size;
	}

	void PushRange(void* start, void* end,size_t n)
	{
		NextObj(end) = _freeList;
		_freeList = start;
		_size += n;
	}
	//批量化取出一段内存
	void PopRange(void*& start, void*& end, size_t n)
	{
		assert(n >= _size);
		start = _freeList;
		end = start;
		for (size_t i = 0;i < n-1;i++)
		{
			//if(NextObj(end))end = NextObj(end);
			end = NextObj(end);
		}
		_freeList = NextObj(end);
		NextObj(end) = nullptr;
		_size -= n;
	}

	/*void PopRange(void*& start, void*& end, size_t n)
	{

	}*/


	void* pop()
	{
		assert(_freeList);
		//头删
		void* obj = _freeList;
		_freeList = NextObj(obj);
		--_size;
		return obj;
	}

	bool Empty()
	{
		return _freeList == nullptr;
	}

	size_t& MaxSize() 
	{
		return _maxSize;
	}

	size_t Size()
	{
		return _size;
	}
private:
	void* _freeList=nullptr;
	size_t _maxSize = 1;
	size_t _size=0;
};

//计算对象大小的对齐映射规则
class SizeClass
{
public:
	// 整体控制在最多10%左右的内碎⽚浪费
	// [1,128]				8byte对⻬		freelist[0,16)
	// [128+1,1024]			16byte对⻬		freelist[16,72)
	// [1024+1,81024]		128byte对⻬		freelist[72,128)
	// [8*1024+1,641024]	1024byte对⻬	freelist[128,184)
	// [64*1024+1,256*1024] 8*1024byte对⻬	freelist[184,208)
	static inline size_t _RoundUp(size_t size, size_t alignNum)
	{
		return ((size + alignNum - 1) & ~(alignNum - 1));
	}

	static inline size_t RoundUp(size_t size)
	{
		if (size <= 128)
		{
			return _RoundUp(size, 8);
		}
		else if (size <= 1024)
		{
			return _RoundUp(size, 16);
		}
		else if (size <= 8 * 1024)
		{
			return _RoundUp(size, 128);
		}
		else if (size <= 64 * 1024)
		{
			return _RoundUp(size, 1024);
		}
		else if (size <= 256 * 1024)
		{
			return _RoundUp(size, 8 * 1024);
		}
		else
		{
			return _RoundUp(size, 1<<PAGE_SHIFT);
		}
	}

	static inline size_t _Index(size_t bytes, size_t align_shift)
	{
		return ((bytes + ((static_cast<size_t>(1) << align_shift) - 1)) >> align_shift) - 1;
	}

	/*static inline size_t _Index(size_t bytes, size_t align_shift)
	{
		return ((bytes + (1 << align_shift) - 1) >> align_shift) - 1;
	}*/
	// 计算映射的哪⼀个⾃由链表桶
	static inline size_t Index(size_t bytes)
	{
		assert(bytes <= MAX_BYTES);
		// 每个区间有多少个链
		static int group_array[4] = { 16, 56, 56, 56 };
		if (bytes <= 128)
		{
			return _Index(bytes, 3);
		}
		else if (bytes <= 1024)
		{
			return _Index(bytes - 128, 4) + group_array[0];
		}
		else if (bytes <= 8*1024)
		{
			return _Index(bytes - 1024, 7) + group_array[1] + group_array[0];
		}
		else if (bytes <= 64 * 1024)
		{
			return _Index(bytes - 8 * 1024, 10) + group_array[2] +
				group_array[1] + group_array[0];
		}
		else if (bytes <= 256 * 1024)
		{
			return _Index(bytes - 64 * 1024, 13) + group_array[3] +
				group_array[2] + group_array[1] + group_array[0];
		}
		else
		{
			assert(false);
			return -1;
		}
	}

	// ⼀次thread cache从中⼼缓存获取多少个
	static size_t NumMoveSize(size_t size)
	{
		if (size == 0)
			return 0;
		// [2, 512]，⼀次批量移动多少个对象的(慢启动)上限值
		// ⼩对象⼀次批量上限⾼
		// ⼩对象⼀次批量上限低
		size_t num = MAX_BYTES / size;
		if (num < 2)
			num = 2;
		if (num > 512)
			num = 512;
		return num;
	}

	// 计算⼀次向系统获取⼏个⻚
// 单个对象 8byte
// ...
// 单个对象 256KB
	static size_t NumMovePage(size_t size)
	{
		size_t num = NumMoveSize(size);
		size_t npage = num * size;
		npage >>= PAGE_SHIFT;
		if (npage == 0)
			npage = 1;
		return npage;
	}
};


struct Span
{
	PAGE_ID _pageId = 0;//大块内存的起始页号
	size_t _n = 0;//页数

	Span* _next = nullptr;//双向链表的结构
	Span* _prev = nullptr;
	size_t objectsize = 0;//切好的小对象的大小
	size_t _useCount = 0;//切成小块内存，被分配给thread cache的计数
	void* _freeList = nullptr;//切成小块内存的自由链表
	bool _isuse = false;
};

//带头双向循环链表
class SpanList
{
public:
	SpanList()
	{
		_head = new Span;
		_head->_next = _head;
		_head->_prev = _head;
	}
	//任意位置插入
	void Insert(Span* pos, Span* newspan)
	{
		assert(pos);
		assert(newspan);
		Span* prev = pos->_prev;
		prev->_next = newspan;
		newspan->_prev = prev;
		newspan->_next = pos;
		pos->_prev = newspan;
	}
	//头插
	void PushFront(Span*span)
	{
		Insert(Begin(), span);
	}
	//取出内存块
	Span* PopFront()
	{
		Span* front = _head->_next;
		Erase(front);
		return front;
	}

	Span* Begin()
	{
		return _head->_next;
	}

	Span* End()
	{
		return _head;
	}

	void Erase(Span* pos)
	{
		assert(pos);
		//assert(pos != _head);
		//条件断点
		//查看栈帧
		/*if (pos == _head)
		{

		}*/
		Span* prev = pos->_prev;
		Span* next = pos->_next;

		prev->_next = next;
		next->_prev = prev;
	}

	bool Empty()
	{
		return _head->_next == _head;
	}
	/*void Lock()
	{
		_mtx.lock();
	}

	void UnLock()
	{
		_mtx.unlock();
	}*/
	std::mutex _mtx;//桶锁
private:
	Span* _head;
	
};